Subsurface well safety apparatus

ABSTRACT

A subsurface well safety apparatus for installation in a well fluid production tubing in a casing which is responsive to the casing pressure. A mandrel having a first open bore passageway and a second passageway laterally offset from the first passageway and a safety valve positioned in the mandrel first passageway. The valve including pressure responsive means acting to control the safety valve and in communication and controlled by pressure in the second mandrel passageway. The first mandrel passageway including first and second spaced apart smooth portions for receiving spaced apart seals on the safety valve and including latch receiving means above the smooth portions for receiving the well lock for supporting the safety valve in the first passageway. A safety valve including an outer valve body having first and second spaced seals with a flap valve pivotally carried at the lower end of the valve body for normally closing the bottom of the valve body and an inner tubular member telescopically movable in the valve body which holds the flap valve in the downward position when the inner member projects out the bottom of the valve body and a plurality of longitudinally spaced pistons connected to the exterior of the inner member, the valve body including an opening leading to the top side of each piston and in communication with the mandrel second passageway for receiving a control fluid acting to keep the valve open.

United States Patent [72] Inventors Harold Edward McGowen,.lr.;

Primary Examiner-James A. Leppink' Attorneys-James F. Weiler, Jefferson D. Gill Stout, Paul L. De Verter, 1]

er, William A.

Gllbert Henry Tausch, both of Houston, Tex.

, Dudley R. Bobie, Jr. and Henry 0 N m 0, @3 e s new SJ 0. d N w 1 n mw a AFP ll] -25 224 [.11

ABSTRACT: A subsurface well safety apparatus for installag in a casing which is d m a w mm n, n m mu no CH C e n 8 .Q S A 1 3 7 .1

tion in a well fluid production tubin responsive to the casing pressure. A m open bore pass set from the fi the mandrel andrel having a first ageway and a second passageway laterally offrst passageway and a safety valve positioned in first passageway. The valve including pressure he safety valve and in y pressure in the second manfirst mandrel passageway including first responsive means acting to control t I communication and controlled b portions for receiving spaced and including latch receiving portions for receiving the well lock alve in the first passageway. A safety valve including an outer valve body having first and second spaced seals with a flap valve R m m.

P m mm V m a T m mm E u "n F. m mm mm mm F m mm L M mm Em m Wm F m m mm m shC a.

mus m s ru F H H Um u w ow of the valve body for normal] ng the bottom of the valve b ody and an inner tubular member telescopically movable in he valve body which holds the flap valve in the downward position when the inner member projects out the bottom of m w T MA 1? S QE T mA rT ms n m H N U N U the valve body and a plurality of] connected to the exterior of the inn including an opening leading to the top side 0 in communication with the mandrel second receiving a control fluid acting to keep the valv 44 22 HQ 66 66 ll 3,078,923 2/1963 Tausch......................... 3,065,794 11/1962 Page....,...

2,963,089 12/1960 Sizer........

3,454,093 7/1969 Garrett....

6/1963 Brown et Patented Dec. 14, 1971 3, 21,042

2 Sheets-Sheet 2 fy z/l I 25;

BACKGROUND OF THE INVENTION Various safety valves have been used in the past in a well tubing to shutoff production of well fluid from oil or gas well such as shown in U.S. Pat. No. 3,265,l34.

The present invention is directed to a subsurface well safety apparatus for installation in a well fluid production tubing positioned in a well casing which is controlled by the pressure in the casing. A mandrel may be provided having a first open bore passageway for alignment with the well tubing in which a safety valve is provided, and including a second elongate passageway laterally offset from the first passageway and which is in communication with the annulus between the well tubing and the casing whereby the mandrel may be used to accomplish other subsurface functions such as gas lift and the casing pressure may be used to control the actuation of the safety valve. Thus under normal flow conditions, the well safety valve is in the open position, but the safety valve is closed in the event failure occurs at the well head causing the casing pressure to drop and the safety valve will close and shut off well production as a result of undesired increase flow through the tubing or a malfunction in the tubing system downstream of the self-acting safety valve.

The pressure between the tubing and the casing or casing pressure may be used to control the safety valve, but by the use of a mandrel the present well safety apparatus may be operated to insure that any high bottom hole pressure in the tubing is not allowed to flow into the and damage the casing.

SUMMARY The present invention is directed to providing a well safety valve that is controlled by casing pressure. In addition, a mandrel may be provided in a well fluid production tubing positioned in a casing with a safety valve positioned in the mandrel first passageway in alignment with the well tubing and in communication with the pressure in the annulus between the tubing and the casing through the second mandrel passageway which controls the actuation of the safety calve.

A further objectof the present invention is the provision of an improved subsurface well safety valve having an outer tubular body with first and second spaced seals around the exterior with a flap valve pivotally carried at the lower end ofthe body for normally closing the bottom of the body and an inner tubular member telescopically movable in the body and which holds the flap valve in the downward and open position when the inner member projects below the bottom of the body. A plurality of longitudinally spaced pistons may be connected to the exterior of the inner member and slidable on the interior of the valve body with the inner member and the valve body forming a closed chamber below each of the pistons with the body having an opening leading to the top side of each piston for supplying a control fluid thereto acting to keep the valve open. Further control of the actuation of the valve may be provided by providing spring means between the body and the inner member tending to move the inner member upwardly and close the valve and upper and lower seals may be provided between the valve body and the inner member with the upper wall portion of the inner member being thicker than the lower wall portion of the inner member thereby providing a greater downwardly facing area on the inner member whereby pres sure in the inner member acts to move the member downwardly and open the valve.

A further object of the present invention is the provision of an improved mandrel for installation in a subsurface well safety apparatus in which the mandrel has a first open bore passageway for alignment with the well tubing and includes first and second spaced apart smooth portions for receiving spaced apart seals on a safety valve and the first passageway includes latch-receiving means above the smooth portions for receiving a well lock for supporting a safety valve in the first passageway with the mandrel body including a second passageway laterally offset from the first passageway and ineluding a flow control unit housing at the upper end of the second passageway for receiving a flow control unit with the second passageway including an opening communicating exteriorly of the mandrel body for receiving causing pressure with the second passageway being in communication with the first passageway at a position between the first and second smooth portions for supplying casing pressure to a safety valve positioned in such first passageway.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. IA is a fragmentary elevational view, partly in cross section, illustrating the upper portion of the preferred embodiment of the subsurface well safety apparatus of the present invention in use with the casing pressure regulating a safety valve,

FIG. 1B is a continuation of FIG. IA showing the lower portion of the present apparatus showing the safety valve in the open position,

FIG. 2A is a fragmentary elevational view, partly in cross section, showing the upper portion of the present invention in use with the safety valve closed and the casing pressure blocked off whereby the safety valve may be removed without allowing tubing pressure to flow to the casing, and

FIG. 2B is a continuation of FIG. 2A showing the lower portion of the apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings and particularly FIGS. IA and IB, the reference numeral I0 generally indicates subsurface well safety apparatus of the present invention and may generally include a mandrel I2 and a well safety valve 14. The mandrel I2 includes suitable connections, such as threads 16 at the top and 18 at the bottom, for connection to conventional well tubing (not shown) in a well bore, and is generally positioned in a casing 20 for conducting fluid production such as oil or gas from a production zone and up the tubing to the surface.

The mandrel 12 includes a first passageway 22 having an open bore in alignment with the well tubing for passage of well tools. The mandrel I2 of the present invention includes in the first passageway 22, as best seen in FIG. 18, first and second spaced-apart smooth portions 24 and 26for receiving and coacting with spaced-apart seals for sealing about the safety valve 14, which will be more fully described hereinafter. In addition, the first passageway may include suitable holding means such as latch-receiving means such as notch 28 positioned above the smooth portions 24 and 26 for receipt of holding means such as a well lock 30 for supporting the safety valve 14 in the first passageway 22 at the desired location.

The mandrel I2 also includes a second passageway or side I pocket 24 which is laterally offset from but in communication with the first passageway 22 at the op thereof as is conventional. The second passageway 34 includes a housing 36 at its upper end for receipt of suitable flow control units 38 which may be inserted into and removed from the flow control housing 36 by conventional setting and retrieving tools (not shown). Openings 37 are provided in the mandrel 12 between the second passageway 34 and the exterior of the mandrel 12 whereby fluid such as gas pressure in the annulus 40 between the tubing and the casing 20 is admitted into the second passageway 34. It is to be particularly noted that the lower end of the second passageway 34 is in communication with the first passageway 22 (FIG. IB) at a location between the first and second spaced smooth portions 24 and 26 thereby supplying gas under pressure from the annulus -40 between the tubing and the casing 20 to the safety valve 14 for controlling the actuation of the safety valve I4 as will be more fully described hereinafter.

One of the functions of the safety valve I4 is to prevent the well from over producing or blowing willd should surface controls fail or become damaged. Thus the safety valve 14 is positioned in the first passageway 22 in the mandrel 12 and remains open to allow flow therethrough under proper operating conditions, but closes at a predetermined pressure drop across the valve 14 or a decrease in control pressure.

The safety valve 14 includes an outer valve body 42 adapted to be movable in the well tubing and set and retracted from the first passageway 22 of the mandrel l2 and includes seals 44 and 46'(the upper of which may be made a part of well lock 30 for convenience), which coact with the smooth portions 24 and 26,respectively, in the first passageway 22 thereby isolating the pressure in annulus 40 or the casing pressure flowing into the second passageway 34 to a point between the two seals 44 and 46. In addition, seals 44 and 46 prevent the well pressure in the tubing and first passageway 22 from communicating with the lower end of the second passageway 34. Thus, the seals 44 and 46 prevent fluid pressure in the tubing and first passageway 22 from entering the lower end of passageway 34 and possibly damaging the casing 20. A flap valve 48 is pivotally carried about pivot 50 and includes spring means (not shown) for normally pivoting the flap valve 48 upwardly to close off the bottom of the valve'body 42 and block the flow of fluids upwardly through the first passageway 22 and through the well tubing to the surface. An inner tubular member 52 is telescopically movable in the valve body 42 and when the inner member 52 projects out of the bottom of the valve body 42 the member holds the flap valve 48 in the downward and open position thereby permitting fluid flow through the safety valve 14 and the first passageway 22.

In order to provide a control to maintain the inner tubular member 52 in a downward position to keep the flap valve 48 open, one or more pistons, here shown as pistons 56, 58 and 60, are provided connected to the exterior of the inner member 52 and slidable on the interior of the valve body 42. The valve body 42 is provided with openings 62, 64 and 66 above the pistons 56, 58 and 60, respectively, and the openings are in communication with the lower end of the second passageway 34 of the mandrel 12 to receive a control fluid such as casing pressure from the casing annulus which acts on the top of the pistons 56, S8 and 60 to keep the safety valve 14 in the open position. While a single piston may be sufficient, depending upon the pressures and conditions involved, the pressure in the annulus 40 between the tubing and the casing 20 would generally be considerably lower than the welltubing pressure and the multiple longitudinally spaced and stacked pistons 56, 58 and 60 may be desirable to provide a sufl'lcient force to keep the safety valve in the open position while still maintaining a sufficient flow through the safety valve 14. It is to be noted that closed chambers 70, 72 and 74 are formed below the pistons 56, 58 and 60, respectively, by the exterior of the inner tubular member 52 and the interior of the valve body 42 which are preferably at atmospheric pressure and thus do not provide any obstacle against which the pistons are required to operate. Thus the pressure in the annulus 40 may be controlled conveniently from the surface to control the opening and closing of the safety valve 14.

It is also noted that the inner tubular member 52 and the outer valve body 42 have an upper seal 76 and a lower seal 78 therebetween and that the upper section 80 of the tubular member 52 may be thicker than the lower section 82 of the tubular member 52 whereby the upwardly facing shoulder 84 has a greater area than the lower or downwardly directed shoulder 86 at the bottom of the member 52. Thus, because of the differential difference in area between the surfaces of the shoulders 84 and 86, a normal static pressure force may be provided acting to hold the inner tubular member 52 in the downward position to also aid in holding the flap valve 48 in the open position. However, upon over production or blowing wild of the fluid in the tubing, the pressure drop across the inner tubular member 52 would rise to a predetennined value, overcoming the force of the control fluid acting on the pistons 56, 58 and 60, and automatically move the inner tubular member 52 upwardly allowing the flap valve 48 to close and shut off the upper flow of fluid through the first passageway 22 and the well tubing. In addition, a spring 88 may be provided between shoulders on the outer valve body 42 and the inner valve body 52 yieldably urging the inner tubular member 52 in the upper direction to provide a more positive closing action when the predetermined pressure drop occurs across the valve 14.

While the well safety valve 14 may be held in position in the first passageway 22 of the mandrel 12 by any suitable means, a conventional well lock 30 such as type-M sold by Cameo, lncorporated, is satisfactory and includes latching dogs 90 which coact with the latch-receiving means 28 in the first passageway 22 of the mandrel 12 for retrievably holding the safety valve 14 in position.

While the preferred embodiment of the present invention includes the mandrel 12 whereby the mandrel may be used to accomplish other surface functions and for the purpose of allowing the safety valve to be removed without subjecting the casing 20 to tubing pressure, the mandrel 12 may be omitted and the safety valve 14 inserted in the well tubing and controlled by the casing pressure. That is, the second passageway 34 may be omitted and the safety valve 14 would be in direct communication with the annulus 40 through one or more the ports 62, 64 and 66.

In use, as shown in FIGS. 1A and 1B, the casing pressure from the annulus 40 between the tubing and the casing 20 enters the openings 36 and flows into the second passageway 34 and as best seen in FIG. 1B flows through the openings 62, 64

and 66 of the valve body 42 of the safety valve 14 and acts on the pistons 56, 58 and 60 to hold the safety valve 14 and member 52 in a downward position holding the flap valve 48 open to allow fluid production to flow through the tubing and the first passageway 22 and to the surface. As shown in FIG. 1A, the flow control unit 38 which is positioned in the flow control housing 36 is shown as a dummy plug such as type-E as manufactured by Camco, Incorporated, wherein the entire casing pressure is used solely to regulate the safety valve 14. However, by using the mandrel 12, other normal well functions may be provided such as gas lift operations by replacing the dummy plug 38 with any suitable conventional and desired flow control unit. In any event, the actuation of the safety valve 14 is suitably controlled by the casing pressure. It is also to be noted that if an equipment failure occurs at the well head at the surface which would cause casing pressure in the annulus 40 to drop, the control force on top of the pistons 56, 58 and 60 would be removed and the spring 86 would act to close the safety valve 14. Or in the event that the production through the well tubing and first passageway 22 is over producing or flowing wild and the surface controls fail or become damaged, the differential pressure across the safety valve 14 will increase to a predetermined value and overcome the control force on the pistons to move the inner tubular member 52 upwardly and allow the spring loaded valve flap 48 to close thereby closing the safety valve 14.

However, the well casing 20 is not generally designed to withstand the well pressure to which the tubing and mandrel 12 may be subjected. The present well safety apparatus 10 may be operated to use the pressure in the casing annulus to control the safety valve 14, but yet prevents the tubing pressure in the tubing and first passageway 22 in the mandrel 12 from flowing into the annulus 40 between the mandrel l2 and the casing 20. That is, assuming that the safety valve 14 has moved to a closed position, as best seen in H0. 28, due to high-flow conditions in the tubing and first passageway 22 or loss of casing pressure, the safety valve 14 could not be removed from the apparatus 10, even assuming that the surface controls were acting satisfactorily in the installation shown in FIGS. IA and 18 without subjecting the casing 20 to the undesirable high pressures in the tubing and fluid passageway 22. Therefore, prior to pulling the well lock 30 and safety valve 14, the dummy plug 38 shown in FIG. 1A would be removed by conventional wireline retrieving tools and replaced, as best seen in FIG. 2A with a blanking plug having seals 102 and 104. Thus, when the blanking plug 100 is placed in the housing 36, the seals 102 and 104 strattle the lOlOl4 0206 openings as closing off both ends of the second passageway 34 from the first passageway 22, after which the well lock 30 and safety valve 14 may be safely removed without subjecting the casing to undesired high pressures.

The present invention, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned as well as others inherent therein.

What is claimed is:

l. A subsurface well safety apparatus for installation in a well fluid production tubing comprising,

a mandrel having a first elongate passageway adapted to be aligned with the well tubing and a second elongate passageway laterally offset from the first passageway, said second passageway including a flow control unit housing at the upper end for receiving a flow control unit, said mandrel including an opening communicating from the outside of the mandrel to said second passageway,

a safety valve positioned in the first passageway, said valve including pressure responsive means acting in a direction to open said valve, and

said second passageway in communication with the valve pressure-responsive means for actuating said pressureresponsive means.

2. The apparatus of claim 1 wherein said valve pressureresponsive means includes a plurality of pistons one side of which are in communication with the second passageway and a closed chamber in contact with the second side of each piston.

3. The apparatus of claim l wherein said valve includes means responsive to flow through the valve acting to close said valve.

4. A subsurface well safety mandrel for installation in a well fluid-production tubing comprising,

a mandrel body having a first open bore passageway for alignment with the well tubing,

said first passageway including first and second spaced apart smooth portions for receiving spaced-apart seals on a safety valve,

said first passageway including latch receiving means above said smooth portions for receiving a well lock for supporting a safety valve in said first passageway,

said mandrel body including a second passageway laterally offset from the first passageway, said second passageway including a flow control unit housing at the upper end in communication with said first passageway above said first and second smooth portions for inserting and removing a flow control unit and including an opening in the housing communicating exteriorly of the mandrel body, and said second passageway being in communication with the first passageway at a position between the first and second smooth portions.

5. In combination with the mandrel of claim 6 of a well safety valve comprising,

an outer tubular valve body having first and second spaced seals around the exterior of the valve body for scaling in the first passageway at said first and second smooth portions,

a valve carried on the lower end of the valve body for normally closing the bottom of the valve body,

an inner tubular member telescopically movable in the valve body and which holds the valve in the open position when the inner member projects out of the bottom of the valve body,

piston means connected to the exterior of the inner member and slidable on the interior ofthe valve body,

the valve body having an opening leading to the top side of said piston means and in communication with the mandrel second passageway for receiving a control fluid thereto tending to keep the valve open,

a closed chamber formed between the member and valve body below said piston means, and

a well lock connected to the safety valve and including latch means for locking in the mandrel latch-receiving means.

6. The apparatus of claim 4 including, a first flow control unit adapted to be positioned in the flow control unit housing for blocking the upper end of the second passageway from the first passageway but allowing communication from the opening in the housing to the first passageway between the first and second smooth portions.

7. The apparatus of claim 6 including,

a second flow control unit adapted to replace the first flow control unit and close the opening in the housing.

8. A subsurface well safety valve comprising,

an outer tubular body having first and second spaced seals around the exterior for sealing in a well tubing,

a'flap valve pivotally carried on the lower end of the body for normally closing the bottom of the body,

an inner tubular member telescopically movable in the body and which holds the flap valve in the downward open position when the inner member projects below the bottom of the body,

a plurality of longitudinally spaced pistons connected to the exterior of the inner member and slidable on the interior of the body,

the body having an opening leading to the top side of each piston for supplying a control fluid thereto tending to keep the valve open,

a closed chamber formed between the member and the body below each of the pistons,

spring means between the body and the inner member tending to move the inner member upwardly and close the valve, upper and lower seal means between the body and the inner member and the upper wall portion of the inner member being thicker than the lower wall portion of the inner member thereby providing a greater downwardly facing area whereby pressure in the inner member acts to move the tubular member downwardly for holding the valve open. 9. A subsurface well safety apparatus for installation in a well fluid-production tubing positioned in a casing comprising, a mandrel body having a first open bore passageway for alignment with the well tubing, and a second elongate passageway laterally offset from the first passageway, said second passageway including a flow control unit housing at the upper end for receiving a flow control unit, said mandrel including an opening communicating from the outside of the mandrel body to the second passageway for admitting pressure in the annulus between the tubing and the casing into the second passageway, said second passageway in communication with the first passageway, a safety valve positioned in the first passageway including,

an outer tubular valve body having first and second spaced seals around the exterior for scaling in the first passageway, a valve carried on the valve body for normally closing the body, an inner tubular member telescopically movable in the valve body and which holds the valve in the open position when the inner member projects downwardly, at least one piston connected to the exterior of the inner member and slidable on the interior of the valve body, said valve body and member forming a closed chamber against the bottom of the piston, the valve body having an opening leading to the top side of the piston for supplying a control fluid thereto tending to keep the valve open, and positioned to be in communication with the second passageway of the mandrel. 10. The apparatus ofclaim including, the first passageway of the mandrel including latch-receiving means, and a well lock connected to the safety valve and including latch means for locking in the mandrel latch-receiving means for supporting the safety valve. 

1. A subsurface well safety apparatus for installation in a well fluid production tubing comprising, a mandrel having a first elongate passageway adapted to be aligned with the well tubing and a second elongate passageway laterally offset from the first passageway, said second passageway including a flow control unit housing at the upper end for receiving a flow control unit, said mandrel including an opening communicating from the outside of the mandrel to said second passageway, a safety valve positioned in the first passageway, said valve including pressure responsive means acting in a direction to open said valve, and said second passageway in communication with the valve pressureresponsive means for actuating said pressure-responsive means.
 2. The apparatus of claim 1 wherein said valve pressure-responsive means includes a plurality of pistons one side of which are in communication with the second passageway and a closed chamber in contact with the second side of each piston.
 3. The apparatus of claim 1 wherein said valve includes means responsive to flow through the valve acting to close said valve.
 4. A subsurface well safety mandrel for installation in a well fluid-production tubing comprising, a mandrel body having a first open bore passageway for alignment with the well tubing, said first passageway including first and second spaced apart smooth portions for receiving spaced-apart seals on a safety valve, said first passageway including latch receiving means above said smooth portions for receiving a well lock for supporting a safety valve in said first passageway, said mandrel body including a second passageway laterally offset from the first passageway, said second passageway including a flow control unit housing at the upper end in communication with said first passageway above said first and second smooth portions for inserting and removing a flow control unit and including an opening in the housing communicating exteriorly of the mandrel body, and said second passageway being in communication with the first passageway at a position between the first and second smooth portions.
 5. In combination with the mandrel of claim 6 of a well safety valve comprising, an outer tubular valve body having first and second spaced seals around the exterior of the valve body for sealing in the first passageway at said first and second smooth portions, a valve carried on the lower end of the valve body for normally closing the bottom of the valve body, an inner tubular member telescopically movable in the valve body and which holds the valve in the open position when the inner member projects out of the bottom of the valve body, piston means connected to the exterior of the inner member and slidable on the interior of the valve body, the valve body having an opening leading to the top side of said piston means and in communication with the mandrel second passageway for receiving a control fluid thereto tending to keep the valve open, a closed chamber formed between the member and valve body below said piston means, and a well lock connected to the safety valve and including latch means for locking in the mandrel latch-receiving means.
 6. The apparatus of claim 4 including, a first flow control unit adapted to be positioned in the flow control unit housing for blocking the upper end of the second passageway from the first passageway but allowing communication from the opening in the housing to the first passageway between the first and second smooth portions.
 7. The apparatus of claim 6 including, a second flow control unit adapted to replace the first flow control unit and close the opening in the housing.
 8. A subsurface well safety valve comprising, an outer tubular body having first and second spaced seals around the exterior for sealing in a well tubing, a flap valve pivotly carried on the lower end of the body for normally closing the bottom of the body, an inner tubular member telescopically movable in the body and which holds the flap valve in the downward open position when the inner member projects below the bottom of the body, a plurality of longitudinally spaced pistons connected to the exterior of the inner member and slidable on the interior of the body, the body having an opening leading to the top side of each piston for supplying a control fluid thereto tending to keep the valve open, a closed chamber formed between the member and the body below each of the pistons, spring means between the body and the inner member tending to move the inner member upwardly and close the valve, upper and lower seal means between the body and the inner member and the upper wall portion of the inner member being thicker than the loweR wall portion of the inner member thereby providing a greater downwardly facing area whereby pressure in the inner member acts to move the tubular member downwardly for holding the valve open.
 9. A subsurface well safety apparatus for installation in a well fluid-production tubing positioned in a casing comprising, a mandrel body having a first open bore passageway for alignment with the well tubing, and a second elongate passageway laterally offset from the first passageway, said second passageway including a flow control unit housing at the upper end for receiving a flow control unit, said mandrel including an opening communicating from the outside of the mandrel body to the second passageway for admitting pressure in the annulus between the tubing and the casing into the second passageway, said second passageway in communication with the first passageway, a safety valve positioned in the first passageway including, an outer tubular valve body having first and second spaced seals around the exterior for sealing in the first passageway, a valve carried on the valve body for normally closing the body, an inner tubular member telescopically movable in the valve body and which holds the valve in the open position when the inner member projects downwardly, at least one piston connected to the exterior of the inner member and slidable on the interior of the valve body, said valve body and member forming a closed chamber against the bottom of the piston, the valve body having an opening leading to the top side of the piston for supplying a control fluid thereto tending to keep the valve open, and positioned to be in communication with the second passageway of the mandrel.
 10. The apparatus of claim 10 including, the first passageway of the mandrel including latch-receiving means, and a well lock connected to the safety valve and including latch means for locking in the mandrel latch-receiving means for supporting the safety valve. 